title: Preoperative acetazolamide SPECT is useful for predicting outcome of shunt operation in idiopathic normal pressure hydrocephalus patients.
abstract: OBJECTIVE
  Good outcome of shunt surgery for idiopathic normal pressure hydrocephalus (iNPH) patients are highly dependent on accurate preoperative assessments. Acetazolamide ethylcysteinate-dimer-single photon emission computer tomography (SPECT) was applied to iNPH patients for more exact preoperative evaluation.
  
  
  METHODS
  Sixty-five patients were categorized into 3 groups: group I (normals, n = 30), group II (with ventriculomegaly due to age-relating changes, n = 10), and group III (who underwent shunt surgery based on the diagnosis of iNPH, n = 25). Acetazolamide SPECT was performed in all patients, and mini-mental state examination (MMSE) was performed before and 1 month after the surgery in group III.
  
  
  RESULTS
  Acetazolamide SPECT study demonstrated normal increase of cerebral blood flow (CBF, more than 40%) in groups I and II. Group III was classified into 2 subgroups on the examination; a mean increasing percentage (%increase) of CBF was less than 20% in group IIIa and more than 40% in group IIIb. One month after the surgery, acetazolamide SPECT showed normal %increase of CBF in IIIa, and the increase in postoperative MMSE score was significantly greater in group IIIa than IIIb (P < 0.05). In iNPH patients, less than 20% increase in preoperative acetazolamide SPECT predicted improvement of MMSE score with 100% sensitivity and 60% specificity.
  
  
  CONCLUSIONS
  Poor %increase of CBF by acetazolamide implies a low capacity for vasodilation in the brain due to compression and stretching by ventriculomegaly. Acetazolamide SPECT study is not an absolute examination but one of the valuable supplementary objective examinations to determine the surgical indication in iNPH-suspected patients.
authors.affiliation: Department of Neurosurgery, Rissho Kosei-kai Hospital, Tokyo. merrityamada@hotmail.co.jp
authors.forename: Shoko M
authors.initials: SM
authors.lastname: Yamada
authors.forename: Noritaka
authors.initials: N
authors.lastname: Masahira
authors.forename: Yu
authors.initials: Y
authors.lastname: Kawanishi
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Fujimoto
authors.forename: Keiji
authors.initials: K
authors.lastname: Shimizu
mesh_terms: D000086:Acetazolamide / Q000627:therapeutic use*; D002557:Cerebrospinal Fluid Shunts; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000503:physiopathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care; D011379:Prognosis; D015899:Tomography, Emission-Computed, Single-Photon; D016896:Treatment Outcome
chemical_list: D000086:Acetazolamide